Some apes, such as chimpanzees and orangutans, can recollect their past, indicating that they bear many similarities to that of humans.
Reuters

A small incident can spontaneously evoke a childhood memory in a person’s life. Similarly, certain apes, such as chimpanzees and orangutans can also remember events from their past, a new study reveals.

According to current understanding, apes cannot recall events, which have occurred more than 72 hours earlier. However, the new study by a team of researchers at the Aarhus University Center on Autobiographical Memory Research, in Denmark, claimed that given the proper clues, chimpanzees and orangutans can remember events from the distant past.

The findings were published in the journal Current Biology on Thursday.

"We have conducted a new experiment which proves that chimpanzees and orangutans are able to remember the task of finding a tool in a particular place and using it correctly. The apes had only performed the task four times before three years earlier", Gema Martin-Ordas, of Aarhus University, said in a statement.

The researchers used specific signals to trigger memories of an experiment that the apes had learned three years ago. During the earlier experiment, the animals watched a researcher hide two different kinds of tools (a long and a short stick) in two different places and were asked to find them.

To test whether the apes could remember a specific event in the past, the researchers conducted yet another experiment. Once again, the primates were introduced to a task where they saw the relevant tool (this time a ball) being hidden and subsequently had to find it.

When the scientists recreated the test, the chimps and orangutans were able to find the right tool quickly, proving that apes can memorize past events.

“I was shocked that the chimpanzees and orangutans found the tools,” National Geographic quoted Martin-Ordas as saying. “I was skeptical. I thought it wouldn’t work, and it did.”

According to the researchers, the complexity of the events the apes had to recall during the experiments indicates that chimpanzees and orangutans' ability to do so bears many similarities to that of humans' capability to recollect events.

“We know that humans often have spontaneous autobiographical memories when given specific clues, in the exact same way as the chimpanzees and orangutans in the experiment. This indicates that, evolutionarily speaking, this spontaneous part of human memory is very old,” Dorthe Berntsen of Aarhus University said.